Patent Literature 1 below is raised as background art of the present technical field. In an abstract of this publication, “to provide a projection-type image display device that does not make a person in a projection image feel uncomfortable and that does not make a person looking at the image feel uncomfortable” is described as an object, and the projection-type image display device “including a driving mechanism driving a person detection means to be movable in a specific direction to adjust a detection range of the person detection means and a control means changing a state of an image that is being projected when the person detection means detects existence of a person” is described as a means to achieve the object.